Techniques for correcting white balance of image data acquired by using an image pickup apparatus, such as a digital camera, are known in the art. White balance correction involves, for instance, changing a ratio among red (R) signals, green (G) signals, and blue (B) signals of image data.
A technique for implementing automatic white balance by identifying the type of the light source by using a photographing exposure value (EV) and correcting white balance based on the type of the light source is disclosed in Japanese Patent No. 3849834 (Patent Document 1). On the other hand, a technique for correcting white balance by identifying the type of the light source based on mean values of R, G, and B components of image data is disclosed in, for instance, Japanese Patent Application Laid-open No. 2004-64468 (Patent Document 2).